白腐菌产锰过氧化物酶条件的研究

白腐菌ＰｈａｎｅｒｏｃｈａｅｔｅｃｈｒｙｓｏｓｐｏｒｉｕｍＭＩＧ．３８３降解桉木时具有显著的选择性,３０天内降解３７．２３％Ｋｌａｓｏｎ木素,７．２９％综纤维素。该菌株产胞外锰过氧化物酶,并在高碳低氧培养基中显示较高酶活,静置液体培养的优化培养条件是（Ｌ＾－１）：１０ｇ葡萄糖,２ｍｍｏｌ酒石酸铵,１０ｍｍｏｌｐＨ４．５醋酸钠缓冲液;１ｇ吐温８０,２ｇＫＨ２ＰＯ４,０．５ｇＭｇＳＯ４．７Ｈ２Ｏ,０．     

白腐菌协同热水预处理对毛白杨化学组分和酶水解效果的影响

【目的】增强真菌预处理的效率和降低热水预处理对反应条件的要求。【方法】综合利用白腐菌和热水预处理毛白杨,分析此方法对毛白杨化学组分和酶水解效果的影响。【结果】白腐菌Lenzites betulinus C5617协同热水处理,损失率最高达70.70%。纤维素在2个预处理阶段都有损失,其中L.betulinus C5617达到29.62%。木质素的降解主要集中在白腐菌预处理阶段,其中L.betulinus C5617降解的酸不溶木素较多,达到了16.98%。综合预处理显著改善了毛白杨的酶水解效果。与只经热水预处理的样品相比较,L.betulinus C5617和P.sanguineus D9497协同热水处理分别引起还原糖得率上升了20.60%和12.23%。【结论】综合预处理降低了热水解对反应条件的要求,节约了预处理成本。     

白腐菌及黑曲霉所产的纤维素复合酶对稻草秸秆的生物降解

研究了白腐菌及纤维素复合酶对稻草秸秆的协同生物降解。结果表明,利用黄孢原毛平革菌固态发酵稻草秸秆的过程中,LiP和MnP的最大活力可以达到28.3U/g和12.6U/g,同时,秸秆中的木质素能被有效降解,但纤维素、半纤维素降解率较低。添加黑曲霉所产的纤维素复合酶能有效地促进秸秆腐熟程度。在接入白腐菌培养10天后,每克稻草添加3 IU纤维素酶液并酶解48h可以使稻草秸秆中纤维素降解53.8%,半纤维素降解57.8%,木质素降解44.5%,干物质损失46.3%。此时细胞壁出现大范围破损,整个组织变得松散,秸秆完全腐熟。     

白腐菌紫外诱变选育高产漆酶突变株及其产酶条件研究

以白腐菌为出发菌株,利用紫外线(UV)进行诱变,筛选高产漆酶突变菌株。通过测定致死率绘制出发菌株的致死曲线,采用PDA-RBBR平板变色法进行初筛,ABTS检测酶活对突变株进行摇瓶复筛。结果表明:利用15 w紫外灯在照射距离为30 cm,照射时间为120 s,致死率为72.1%的条件下进行诱变处理,获得一株高产菌株,其酶活提高79.54%,经过5代传代培养,未见酶活下降,具有较好的遗传稳定性,进一步研究了初始pH值,接种量和培养基装液量等对诱变菌株产酶的影响,结果表明在最佳的培养条件pH值6.0,15%的装液量于28℃下,酶活达214.9 U/L。     

通过碳源与氮源研究白腐菌产漆酶和菌丝体生长的相关性

通过碳源与氮源对白腐菌产漆酶和菌丝体生长的影响 ,定性地研究了白腐菌产漆酶和菌丝体生长的关系。碳源中淀粉最能提高菌丝体的生长量 ,麦芽糖是促进漆酶分泌的最好碳源。氮源中的酒石酸铵能较好地促进漆酶的分泌 ,但几种氮源对菌丝体生长的影响不是很明显。研究显示白腐菌的生长和酶的分泌不同步 ,也不成正相关。     

水稻秸秆腐解复合菌系RSS-4的选育及其腐解特性

采用限制性培养技术与温度梯度诱导相结合的方法, 从四川成都平原多年还田的土壤中筛选、构建出一组在中温条件下对水稻秸秆具有腐解功能的复合菌系RSS-4。该复合菌系在22°C条件下, 稻秆腐解试验表明: pH先升高后降低, 最后稳定在7.20; 纤维素酶活、半纤维素酶活均经历了先升后降的变化趋势, 最高酶活分别为0.91、3.40 U; 到16 d腐解结束时, RSS-4对稻秆、纤维素及半纤维素的降解率分别达到了45.0%、55.5%和44.1%, 而木质素在整个腐解过程中未发生明显的变化; 说明所筛选构建的这组腐解复合菌系可加速稻秆的腐解。同时发现采用未灭菌的筛选方法筛得的复合菌系RSS-4比灭菌所得的RSS-4￠腐解效果要好。     

白腐菌产锰过氧化物酶条件的研究

白腐菌Phanerochaeta chrysosporium MIG. 383降解桉木时具有显著的选择性,30天内降解37．23％Klason木素,7.29％综纤维素。该菌株产胞外锰过氧化物酶,并在高碳低氧培养基中显示较高酶活。静置液体培养的优化培养条件是(L^-1)：10g葡萄糖,2mmol酒石酸铵,10mmol pH4.5醋酸钠缓冲液,1g吐温80,2gK₂PO₄,0.5g MgSO₄·7H₂O,0.1g CaCl₂·2H₂O,lmg VB₁,70ml微量元素混合液：最适产酶温度是37℃。上述条件下,该菌接种后静置培养4天,产锰过氧化物酶活达1840U／L,酶作用最适温度是37℃,最适DH是3.5。     

白腐菌产漆酶的纯化及部分酶学性质

对白腐菌W 1产生的漆酶粗酶液通过超滤浓缩、分子筛和离子交换层析进行纯化 .用SDS PAGE证明该酶的分子量大约为 6 2 4kD .等电聚焦电泳显示该酶的等电点为 3 5 .酶反应的最适温度为 5 0℃ ,最适pH值为 4 5 .此酶氧化DMP的Km 值为 3 84× 10 -5mol L .金属离子对酶活的影响很大 ,其中K+ 、Mn2 + 、Ag+ 对酶活有促进作用 ,Fe2 + 、Fe3 + 、Hg2 + 、Co2 + 、Ba2 + 等对酶活有明显的抑制作用 .酶对部分染料也有一定的脱色效果     

Effect of enzyme extracts isolated from white-rot fungi on chemical composition and in vitro digestibility of wheat straw

A series of in vitro experiments were completed to evaluate the potential of enzyme extracts, obtained from the white-rot fungi Trametes versicolor (TV1, TV2), Bjerkandera adusta (BA) and Fomes fomentarius (FF), to increase degradation of cell wall components of wheat straw. The studies were conducted as a completely randomized design and analysed using one-way ANOVA. Enzyme activities of the extracts, previously obtained from a liquid culture medium, were characterized in terms of laccase and peroxidase for ligninolytic activity. Carboxymethyl cellulase (CMCase) and avicell digesting cellulase (Avicelase) were used for cellulolytic enzyme assays. Wheat straw samples were incubated with enzyme extracts in a citrate buffer (pH 5.0) in a forced air oven at 25 °C for 6 days. In vitro NDF digestibility (IVNDFD), and the rate and extent of NDF fermentation, without and after incubation with the white-rot enzyme extracts, were determined using a gravimetric microbiological method and a gas production technique, respectively. Results from cell wall chemical composition showed that TV2 and BA enzyme extracts decreased NDF concentration (P<0.05) and that TV1 had higher activity (P<0.05) towards cellulose. There was an increase in IVNDFD (P<0.05), resulting from treatment of wheat straw with enzyme extracts from BA, TV1 and TV2, reaching a difference of 13% for TV2 (P<0.05), versus the non-treated straw control. Treatment with enzyme extract from TV2 caused increased gas production (P<0.05) after the first 20 h of incubation, and also increased the maximum rate of gas production, thus enhancing fermentation kinetics. This study indicates that enzyme extracts from white-rot fungi can be used to develop new approaches to overcome low digestibility of some plant cell walls. Utilization of different substrates to produce enzyme extracts can lead to production of viable ligninolytic complexes which could improve the nutritive value of fibrous feeds.     

Impact of white-rot fungi on numbers and community composition of bacteria colonizing beech wood from forest soil

White-rot fungi are important wood-decomposing organisms in forest ecosystems. Their ability to colonize and decompose woody resources may be strongly influenced by wood-inhabiting bacteria that grow on easily utilizable compounds e.g. oligomers of wood-polymers released by fungal enzymes. However, so far, it is not known how white-rot fungi deal with the presence of potential competing bacteria. Here, the effects of two white-rot fungi, Hypholoma fasciculare and Resinicium bicolor, on the numbers and composition of bacteria colonizing sterile beech wood blocks from forest soil are reported. Both total numbers (microscopic counts) and the numbers of cultivable wood-inhabiting bacteria were considerably lower in wood blocks that became colonized by the white-rot fungi than in control blocks. This points to the fungi out-competing the opportunistic bacteria. The presence of white-rot fungi resulted in a change in the relative abundance of families of cultivable bacteria in wood and also in a change of denaturing gradient gel electrophoresis patterns of directly amplified 16S rRNA gene fragments. Analysis of the bacterial community structure in soil adhering to exploratory mycelium (cords) indicated that fungal species-specific effects on bacterial community composition were also apparent in this fungal growth phase.     

Production of cellulases by thermophilic fungi grown on Leptochloa fusca straw

Seven indigenous thermophilic fungi were screened for cellulase and xylanase production when grown on Leptochloa fusca (kallar grass) straw. Aspergillus fumigatus produced the highest activities of 0.4, 2.5, 3.5 and 0.14 U/ml of filter paper cellulase, CM-cellulase, xylanase and -xylosidase, respectively. Sporotrichum thermophile produced 0.47 -glucosidase/ml. Chaetomium thermophile, Humicola grisea and Torula thermophila had lower activities than the other thermophilic fungi.The authors are with the National Institute for Biotechnology & Genetic Engineering, P.O. Box 577, Faisalabad, Pakistan.     

玉米秸秆和异Vc钠生产废液固态发酵生产高蛋白饲料研究

以玉米秸秆为原料,以麸皮和异Vc钠生产废液(WEP)为辅料进行生物蛋白饲料固态发酵研究.通过菌种配伍试验,确定了混菌发酵菌种为白地霉、产朊假丝酵母和枯草芽孢杆菌.在此基础上通过单因素优化试验确定了秸秆蛋白饲料的最优发酵条件:以玉米秸秆(5 g)和麸皮(1 g)为基料,4%WEP营养液,固液比1:4(g/mL),初始pH值4.5;以麸皮浸汁作种子培养液,种龄24 h,各菌接种比例为产朊假丝酵母∶白地霉∶枯草芽孢杆菌=3:1:1,接种量2 mL;28℃、静置发酵2 d,在此条件下,秸秆饲料中真蛋白含量为6.21%,比对照提高了23.95%.该研究为秸秆和异Vc钠生产废液的高质化利用提供了新的思路和途径.     

The effect of phenolic acids and molasses spent wash concentration on distillery wastewater remediation by fungi

The effect of gallic acid, vanillic acid, and molasses spent wash (MSW) concentration on growth and decolourizing capability of four fungi (Geotrichum candidum, Coriolus versicolor, Phanerochaete chrysosporium and Mycelia sterilia) was studied. Fungal growth was inhibited to a varying extent in the presence of gallic and vanillic acid, except for G. candidum, which was unaffected by gallic acid. G. candidum and P. chrysosporium growth rates increased in the presence of increasing concentrations of MSW (up to 50% v/v), however, growth of M. sterilia and C. versicolor was inhibited at spent wash concentrations above 5% (v/v). Increasing the concentration of MSW from 6·25% (v/v) to 12·5% (v/v) increased the decolourizing ability of each fungus, except for M. sterilia. C. versicolor exhibited greatest colour removal with a reduction of 0·43 units at A₄₇₅ (equivalent to 53% colour reduction) after 10 days growth in 12·5% (v/v) MSW.     

Chitosan production from hemicellulose hydrolysate of corn straw: impact of degradation products on Rhizopus oryzae growth and chitosan fermentation

Aims: To examine the potential use of hemicellulose hydrolysate (HH) for the production of chitosan by Rhizopus oryzae and investigate the influence of contents in HH on mycelia growth and chitosan synthesis. Methods and Results: Compared to xylose medium, HH enhanced mycelia growth, chitosan content and production of R. oryzae by 10·2, 64·5 and 82·1%, respectively. During sulfuric acid hydrolysis of corn straw, sugars (glucose, galactose, etc) and inhibitors (formic acid, acetic acid and furfural) were generated. Acetic acid (2·14 g l^?1) and formic acid (0·83 g l^?1) were stimulative, while furfural (0·55 g l^?1) was inhibitory. Inhibitors, at different concentrations, increased the mycelia growth and chitosan production by 24·5–37·8 and 60·1–207·1%. Conclusions: HH of corn straw is a good source for chitosan production. Inhibitors in HH, at proper concentrations, can enhance chitosan production greatly. Significance and Impact of the Study: This work for the first time reported chitosan production from HH. Chitosan production can be greatly enhanced by cheap chemicals such as inhibitors in HH.     

Changes in biochemical constituents of paddy straw during degradation by white rot fungi and its impact on in vitro digestibility

Aims: To improve the digestibility of paddy straw to be used as animal feed by means of selective delignification using white rot fungi. Methods and Results: Solid state fermentation of paddy straw was carried out with some white rot fungi for 60 days. Different biochemical analyses, e.g. total organic matter (TOM) loss, hemicellulose loss, cellulose loss, lignin loss and in vitro digestibility, were carried out along with laccase, xylanase and carboxymethyl cellulase activity. The results were compared with that of a widely studied fungus Phanerochaete chrysosporium, which degraded 464 g kg^?1 TOM and enhanced the in vitro digestibility from 185 to 254 g kg^?1 after 60 days of incubation. Straw inoculated with Phlebia brevispora possessed maximum crude protein. Conclusions: All the tested white rot fungi efficiently degraded the lignin and enhanced the in vitro digestibility of paddy straw. Phlebia brevispora, Phlebia radiata and P. chrysosporium enhanced the in vitro digestibility almost to similar levels, while the loss in TOM was much lesser in P. brevispora and P. radiata when compared to P. chrysosporium. Significance and Impact of the Study: The study reflects the potential of P. brevispora and P. radiata as suitable choices for practical use in terms of availability of organic matter with higher protein value, selective ligninolysis and better digestibility.     

Effect of arbuscular mycorrhizal fungi on phytoextraction by corn (Zea mays) of lead-contaminated soil

The role of arbuscular mycorrhizal fungi (AMF) in lead (Pb) uptake by corn (Zea mays) grown in soil supplemented with Pb was examined. Plants were subjected to four Pb levels: 0 (control); 10 (low); 100 (medium); and 500 mg L(-1) (high). At each Pb level, plants were grown in soil without and with fungicide (benomyl) (20 mg kg(-1)) to suppress AMF activity. Benomyl significantly reduced AMF colonization at high. medium, and zero Pb exposures. Benomyl application resulted in significantly lower concentrations of phosphorus in leaves at low and medium Pb exposures. The benomyl-treated plants had higher Pb and manganese concentrations in leaves than plants not treated with benomyl. In addition, benomyl-treated plants had generally lower concentrations of zinc and copper in leaves than plants not treated with benomyl. These results suggest that the role of AMF in heavy metal uptake is metal specific. Based on this work, the use of benomyl on soils contaminated with Pb can be recommended in phytoextraction.     

接种AM真菌对PAEs污染土壤中微生物和酶活性的影响

土壤灭菌条件下 ,添加 5 0mg·kg-1DEHP和 5 0mg·kg-1DBP ,在温室进行盆栽试验 ,观察土壤施加DEHP与DBP和接种AM真菌 (Acaulosporalavis,光壁无梗球囊霉 ,菌号 :34)后菌根际 (简称A)、菌丝际 (简称B)和常规土 (简称C)中土壤微生物和部分土壤酶活性的变化。结果表明 ,土壤施加DEHP和DBP后 ,A、B和C层土中土壤微生物数量和土壤酶含量下降 ;接种AM真菌后 ,受AM直接影响的A和B层土中细菌、放线菌和真菌数量比不接种低 ,而C层土中三菌数量比不接种高 ;A和B层土中中性磷酸酶和脲酶含量下降 ,脱氢酶含量在A、C层土中下降 ,在B层土中稍有增加 ,AM对土壤脱氢酶活性影响不大。接种AM真菌没有降低DEHP和DBP对土壤微生物生长和土壤酶活性不利影响的程度     

Identification of seven species of hymenopteran parasitoids of Spodoptera frugiperda, using polymerase chain reaction amplification and restriction enzyme digestion

1 The fall armyworm Spodoptera frugiperda is a voracious pest of numerous crops of economic importance throughout the New World. In its native Mexico, larvae can be attacked by several species of parasitic wasps, which are candidate biological control agents against this and other lepidopteran pests. 2 We attempted to survey the parasitoid fauna on S. frugiperda in maize and sorghum fields throughout Mexico. However, our efforts have been hampered by the incomplete development of parasitoid larvae emerging from collected Spodoptera caterpillars. 3 This problem was solved by developing a method to identify seven species of parasitic wasps using polymerase chain reaction amplification and restriction enzyme digestion. This enables the precise determination of the species of those parasitoid larvae that are usually not morphologically identifiable.